/Engine/Source/Runtime/Engine/Public/SkeletalRenderPublic.h
Called byFSkeletalMeshObjectprior to GDME. This allows the GPU skin version to update bones etc now that we know we are going to render
virtual void PreGDMECallback ( class [FGPUSkinCache](API\Runtime\Engine\FGPUSkinCache) * GPUSkinCache, uint32 FrameNumber )